From its rise to power in 1933, the Nazi regime built a series of detention facilities to imprison and eliminate so-called "enemies of the state." Most prisoners in the
early concentration camps were German Communists, Socialists, Social Democrats,
Roma (Gypsies),
Jehovah's Witnesses,
homosexuals, and persons accused of "asocial" or socially deviant behavior. These facilities were called “concentration camps” because those imprisoned there were physically “concentrated” in one location.
After Germany's annexation of
Austria in March 1938, the Nazis arrested German and Austrian Jews and imprisoned them in the
Dachau,
Buchenwald, and
Sachsenhausen concentration camps, all located in Germany. After the violent
Kristallnacht ("Night of Broken Glass") pogroms in November 1938, the Nazis conducted mass arrests of adult male Jews and incarcerated them in camps for brief periods.